Microcidal composition

ABSTRACT

An anolyte composition having sufficient strength and stability to be packaged and marketed to consumers is produced in an electrolytic cell having an ionomeric semi-permeable membrane.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of U.S. Provisional Patent Application No. 61/267,323 filed on Dec. 7, 2009 entitled “Microcidal Composition”, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to a composition having microcidal levels of anolyte or catholyte, or a mixture of both.

Anolyte is a known disinfectant due to its oxidizing content. It has also been known as electrolysed water, electro-activated water or electro-chemically activated water solution. It is produced by the electrolysis of ordinary water containing dissolved sodium chloride. The anolyte produced comprises free available chlorine, primarily in the form of sodium hypochlorite.

Anolyte or catholyte has not been available to the general public. EcaFlo® anolyte solution is available for industrial or hospital use, but is produced in bulk for quick consumption. Its general unavailability is because anolyte or catholyte could not be made with a practical shelf-life of over a month.

SUMMARY OF THE INVENTION

In one aspect, the present invention comprises a method of producing anolyte having a free available chlorine concentration of at least 1000 ppm, comprising the use of an electrolytic cell having an anode compartment and a cathode compartment, separated by a semi-permeable membrane. In one embodiment, the semi-permeable membrane permits cation transport at a greater rate than anion transport. The membrane may be ionomeric and may comprise perfluorocarboxylic acid or perfluorosulfonic acid. In one embodiment, the membrane is a bilayer membrane, comprising one layer comprising perfluorocarboxylic acid and one layer comprising perfluorosulfonic acid.

In another aspect, the invention comprises a composition of anolyte having a concentration of free available chlorine such that the composition still has microcidal activity after prolonged storage. In one embodiment, the composition has a concentration of at least about 1680 ppm of free available chlorine, and in a preferred embodiment, has a concentration of at least about 2000 ppm and more preferably about 4000 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like elements are assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention.

FIG. 1 shows a schematic of one embodiment of an electrolysis reaction scheme for producing anolyte and/or catholyte of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention relates to pre-packaged solutions of anolyte which retains an effective amount of microcidal activity. When describing the present invention, all terms not defined herein have their common art-recognized meanings. To the extent that the following description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention. The following description is intended to cover all alternatives, modifications and equivalents that are included in the spirit and scope of the invention, as defined in the appended claims.

As used herein, “anolyte” means an aqueous solution produced at the anode by the electrolysis of aqueous solutions of sodium or potassium chloride. As used herein, “catholyte” means an aqueous solution produced at the cathode by the electrolysis of aqueous solutions of sodium or potassium chloride.

Suitable solutions of anolyte or catholyte may be produced by an electrolysis reactor, such as that illustrated schematically in FIG. 1. The power source is preferably a DC voltage source, producing between about 20 to 40 amperes. In one embodiment, the DC voltage may be between about 12 V and 48 V, preferably between about 20 and 30 V, such as a 26 V source. The voltage and current provided may vary in accordance with the size of the cell, and the other factors known to those skilled in the art.

In one embodiment, the cathode and anode chambers of the reactor are separated by a semi-permeable membrane, which allows the passage of ions in solution. In one embodiment, the membrane is ionomeric and comprises perfluorocarboxylic acid or perfluorosulfonic acid, or both. In one embodiment, Nafion™ ionomer membranes may be suitable. In one embodiment, the semi-permeable membrane comprises a bilayer membrane comprising perfluorocarboxylic acid and perfluorosulfonic acid film layers. In one embodiment, the perfluorocarboxylic acid membrane is known to have a membrane catalytic deprotonation effect, which causes proton fluxes during electrolysis. Without restriction to a theory, it is believed that ionomeric membranes which permit greater movement of cations than anions are preferred. It is believed that this preferential movement of cations, and relative impedance of anions, is the result of using sulfonated or carboxylated perfluorovinyl ether groups on a tetrafluoroethylene backbone.

A review of Nafion membranes is available in the literature Mauritz, K. A., Moore, R. B. (2004). “State of Understanding of Nafion”. Chemical Reviews 104: 4535-4585, the contents of which are incorporated herein by reference, where permitted.

The electrodes may preferably comprise titanium, which may be uncoated or coated with a noble metal such as platinum or palladium, or a metal oxide, or a mixture of metal oxides. In one embodiment, the coating is electrically conductive, but chemically inert.

In one embodiment, the salt solution comprises either NaCl or KCl, preferably in a concentration of between about 24 to 30 g/l, and is fed through the reactor at a rate such that the residence time in the reactor is between about 8 minutes to about 12 minutes, preferably between about 9-10 minutes. In one embodiment, the flowrate is about 32 litres per hour (or 161/h in each of the cathode and anode compartments). The flowrate and residence time within the reactor may be varied to produce anolytes and catholytes of differing ionic concentrations.

As may be appreciated by those skilled in the art, electrolysis results in protons, cations and positively charged moieties crossing into and accumulating in the cathode chamber, while chloride, anions and negatively charged moieties accumulate in the anode chamber. The fluid exiting from the anode partition is anolyte, while the fluid exiting from the cathode partition is catholyte. The reactor may be pressurized, and in one embodiment, may operate at a pressure of about 80 psi (about 550 kPa). The small amounts of oxygen and hydrogen gas produced by the electrolysis remain in solution at an elevated pressure.

Anolyte may be pH neutral or slightly acidic. Without restriction to a theory, it is believed that anolyte does not contain chlorite (ClO₂ ⁻) and chlorate (ClO₃ ⁻) ions. The free available chlorine in anolyte exists primarily as hypochlorous acid and ions (HClO or ClO⁻), free chlorine (Cl₂) and chloride ion (Cl⁻). Without restriction to a theory, it is believed that hypochlorous acid and ions, free chlorine, and/or chloride ions, are restricted or limited in crossing the ionomeric membrane. As a result, they accumulate in the anolyte to levels not found in the prior art.

Effective solutions of anolyte or catholyte made from either NaCl or KCl that the general public, industries, or institutions can be used to meet their various needs as a sanitizer (hands, tables, etc.) and disinfectant for all stages of cleaning in homes, schools, hospitals, veterinary clinics, ambulances, airplanes, buses, trains, ships or any public building for viruses, bacteria and parasites. It may also be used to stop fungus and applied as a fog or aerosol to kill viruses and bacteria that are air transmitted and if applied to plants is very effective at killing plant bacteria and viruses that can kill plants. Anolyte can be used as an industrial biocide for oil field applications for water used in fracking operating, field stimulation, or to stop algae or other forms of growth in piping or cooling systems of any kind. Anolyte may be used a deodorizer for portable toilets, humans, animals, and chickens, fish, and any place that mercaptans of any kind are produced. Catholyte can be used in dental offices to control pH for patient treatment.

An effective anolyte solution must have a concentration of about 400 ppm (parts per million by weight) of free available chlorine produced in the anolyte. The applicant has determined that a prepackaged solution of anolyte drops about 4 ppm per day in storage. Because one embodiment of the anolyte solution of the present invention has a concentration of at least about 4000 ppm of free chlorine, it can be stored for about 900 days before it reaches an ineffective level. An anolyte composition having a concentration of about 1680 ppm will have a shelf life of about 1 year before it reaches the minimum concentration of about 400 ppm.

The anolyte composition may be stored in dark or opaque containers to reduce ultraviolet or visible light degradation of the product. The containers are preferably sealed to prevent oxidative degradation. The anolyte may be used in liquid form, which may be added to treat water streams or sources, or directly or in a dilute form as a disinfecting agent.

Pre-packaged sealed containers of anolyte may be provided in containers sized for domestic use, such as 1 litre or less. Anolyte may be formulated as gels, creams or lotions, in like manner to alcohol-based hand sanitizers, for personal use. In one embodiment, personal sized containers of less than 100 ml may be provided.

Examples Solution Shelf Life Log Book

1) Produced 1000 liters (tote) on Day1. Free available chlorine tested at 4400 PPM. 2) Tested on Day 144. Free available chlorine tested at 3800 PPM. Total chlorine loss of 600 PPM or 4.16 PPM per day for 144 days. 3) Tested on Day 248. Free available chlorine tested at 3400 PPM. Total chlorine loss of 1000 PPM or 4.03 PPM per day for 248 days 4) Tested on Day 347. Free available chlorine tested at 1800 PPM. Larger daily losses of free available chlorine during this test period. Without restriction to a theory, we believe this is because the storage tote was located in direct sun light for many hours each day.

As will be apparent to those skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the scope of the invention claimed herein. 

1. A method of producing anolyte having a free available chlorine concentration of at least 1000 ppm, comprising the use of an electrolytic cell having an anode compartment and a cathode compartment, separated by a semi-permeable membrane.
 2. The method of claim 1 wherein the semi-permeable membrane permits cation transport at a greater rate than anion transport.
 3. The method of claim 2 wherein the semi-permeable membrane is ionomeric and comprises perfluorocarboxylic acid or perfluorosulfonic acid.
 4. The method of claim 3 wherein the membrane is a bilayer membrane, comprising one layer comprising perfluorocarboxylic acid and one layer comprising perfluorosulfonic acid.
 5. The method of claim 1 wherein the anolyte produced comprises a free available chlorine concentration of at least 1680 ppm.
 6. The method of claim 5 wherein the anolyte produced comprises a free available chlorine concentration of at least 2000 ppm.
 7. The method of claim 6 wherein the anolyte produced comprises a free available chlorine concentration of at least about 4000 ppm.
 8. The method of claim 1 wherein the anode and cathode compartments are pressurized to about 80 psi.
 9. An anolyte composition produced by the method of claim 1, formulated and packaged for general consumer use.
 10. The anolyte composition of claim 9 which is formulated and packaged in a sealed, dark or opaque container, having a capacity of 1 litre or less.
 11. The anolyte composition of claim 9 which retains a minimum level of 400 ppm of free available chlorine, after a storage time of one year.
 12. The anolyte composition of claim 11 in which the free available chlorine degrades at a rate of about 4 ppm per day. 